The mind-blowing heat wave that gripped the southwest half of the United States in late March 2026 joins our semi-subjective top-six list of the meteorologically stunning extreme events this century that have most astonished us. Below is our list, including how the March 2026 mega-event compares to an earlier round of March climate madness.
The role of climate change
We know that climate change is injecting more heat into the atmosphere and ocean system. Heat is energy, which means there is more energy to power extreme weather events — particularly heat waves, droughts, and storms — that would have been virtually impossible in the 20th century.
Since climate change is also fundamentally disrupting atmospheric circulation patterns, we now have mega-unprecedented extreme events occurring with regularity. These circulation changes allow the biggest regional and local heat extremes to intensify by a much larger margin than the roughly 1.4°C increase in average global temperature since preindustrial times.
1. The Central and Eastern U.S. “warm wave” of March 2012
The March heat wave that just scorched the Southwest U.S. and nearby regions bears some uncanny echoes of a similar event that hit its peak in March 2012 over the Midwest and Northeast. In both cases, a large part of the contiguous U.S. experienced highly anomalous — and in many cases unprecedented — March warmth for days on end. Thousands of daily records and many hundreds of monthly records were set in both events. The main difference, as implied in Fig. 1, was that the March 2026 heat wave occurred in a naturally warmer part of the country than the 2012 “warm wave.” So instead of the jaw-dropping 80s Fahrenheit that March 2012 brought to places like Michigan and Nova Scotia, we saw jaw-dropping 100s over the Desert Southwest and southern Great Plains.
Even if its temperatures weren’t quite as sizzling, the March 2012 event was astounding in its own right. It saw the most daily records broken at gold-standard, century-long U.S. climate stations for any month since the infamous Dust Bowl apex of July 1936, as noted in Jeff Masters’ summary blog post published at Weather Underground on April 10, 2012. At least 44 daily records were broken by more than 22°F, and four were smashed by at least 30°F. In 21 cases, a daily low temperature was warmer than the record high for the date. No such analysis has yet been performed for the March 2026 event.
Daily temperature ranges were larger in the dry southwestern air of the 2026 event versus the modified Gulf of Mexico air that predominated in the 2021 event. As a result, the daily highs across March 2026 soared more impressively above average than the daily lows (see embedded Bluesky post below from climatologist Brian Brettschneider).
Nevertheless, once the dust has settled, it’s possible the March 2012 and March 2026 events will end up roughly on par with each other in terms of the extent and strength of temperature departures from average across each event – but with different expressions of those extremes on a daily/monthly-record basis, and in terms of absolute temperature and daily highs versus lows.
Another index to watch: whether the 48-state temperature average for March 2026 breaks the record set in March 2012. The official number will be released with NOAA’s monthly U.S. climate summary on April 8. Even before the true heat wave’s onset, the first half of March 2026 was notably mild nationwide. Preliminary analysis from Brettschneider suggests that March 2026 will easily rank as the warmest March in U.S. history.
2. Climate change and the March heat waves of 2012 and 2026
How much did human-caused climate change influence the March 2012 and March 2026 heat waves? An initial assessment led by Martin Hoerling at the NOAA Earth System Research Laboratories concluded that human-produced warming likely contributed on the order of 5% to 10% of the magnitude of the heat wave on March 12-23, 2012. The report added: “the probability of heat waves is growing as [greenhouse-gas]-induced warming continues to progress.”
Since 2012, research on attribution of extreme events has become more widespread and the techniques more varied, and of course, global warming itself has intensified. Already, rapid-response analyses of the March 2026 heat wave from Climate Central and World Weather Attribution have concluded that the overall extremity of the heat wave would have been virtually impossible without human-caused climate change.
One other important note: the March heat of 2012 segued into a drought-ravaged summer across much of the United States. This happened at the tail end of two years of La Niña conditions – exactly where we are right now. The dry heat and scant precipitation of late March helped to further deplete the already paltry snowpack across most of the U.S. West, both through melting and sublimation (evaporation). This has laid the groundwork for enhanced wildfire and water-supply troubles later this spring and summer, assuming that substantial moisture doesn’t arrive in April or May.
3. The Pacific Northwest and Western Canadian heat wave of June 2021
An extraordinarily strong upper-level high in the Pacific Northwest and Western Canada in late June and early July 2021 led to a catastrophic heat wave, taking an estimated 1,400 lives in the far northwest U.S. and far southwest Canada. Seemingly impossible all-time heat records were set in Portland, Oregon (116°F), Salem, Oregon (117°F), Seattle, Washington (108°F), and most tragically, Lytton, British Columbia – which broke Canada’s all-time national heat record for three consecutive days, hitting a peak of 49.6 degrees Celsius (121.3°F) on Jun. 29 before being largely destroyed by wildfire on June 30.
A rapid-release analysis from World Weather Attribution in July 2021 concluded that “an event such as the Pacific Northwest 2021 heat wave is still rare or extremely rare in today’s climate, yet would be virtually impossible without human-caused climate change. As warming continues, it will become a lot less rare.”
In a post at Weather West on March 11, 2026, climate scientist Daniel Swain noted that the extreme upper ridge responsible for the 2021 heat wave was intensified by a powerful North Pacific storm upstream whose warmth and moisture led to huge amounts of heat being added to the air via condensation. Similarly, Swain argued, moisture condensing in the powerful Kona storm that gave Hawaii record rainfall in March 2026 generated upper-level heat, which was transported downwind via a moist atmospheric river. This extra heat energy fed helped build the upper-level high-pressure system over the Southwest U.S. to record strength, in what Swain called a “somewhat complex and counterintuitive process.”
A very technical but highly insightful (and concerning!) post by Deirdre Des Jardins, “The Diabatic Engine Behind March 2026’s Record-Shattering Western Heat Dome,” dove deeper into the details. Global warming may have significantly contributed to the intensity of these record-strength heat domes in 2021 and now 2026 by pumping more heat energy into the system, she concluded. “A warmer atmosphere holds more moisture … more water vapor is available for latent heat release in the cyclones driving ridge amplification.”
Perhaps even more concerning was Des Jardins’ analysis in part two of her series, “Why the Ridge Keeps Coming Back: The Structural Shift Behind Western Heat Domes.” She wrote, “The March 2026 heat dome was not a bolt from the blue. It was the most extreme pulse in a winter-long pattern that locked the western United States into warmth and the East into cold for months. That warm-West/cool-East dipole has become a recurring feature of North American winters over the past decade, and a growing body of research suggests that the winter atmospheric circulation over North America appears to have shifted, driven by greenhouse-gas forced changes in the jet stream. The atmosphere has been restructured in a way that favors extreme ridges over the West.”
If so, our new normal will be an indefinite continuation of the West’s megadrought, accompanied by record losses in water availability and apocalyptic wildfire seasons (and punctuated by only brief respites, such as 2023–24).
Another ominous sign: A burst of new research on how climate change may be pushing the Pacific Decadal Oscillation toward its negative phase, which favors drought in the U.S. Southwest (see our 2025 post, “Why winter rains keep skipping the Southwest“).
4. The Russian heat wave and drought of 2010
A heat wave of unprecedented intensity struck Russia in the summer of 2010, as the jet stream remained “stuck” in an unusual loop that kept cool air and rain-bearing low-pressure systems far to the north, and to the southeast, where Pakistan endured catastrophic flooding. By July 14, the mercury hit 31 degrees Celsius (87°F) in Moscow, the first day of an incredible 33-day stretch with a maximum temperature of 30 degrees Celsius (86°F) or higher.
Moscow’s old extreme heat record, 37 degrees Celsius (99°F) in 1920, was equaled or exceeded five times in a two-week period from July 26-August 6, 2010, including an incredible 38.2 degrees Celsius (101°F) on July 29. Alexander Frolov, head of Russia’s weather service, said in a statement, “Our ancestors haven’t observed or registered a heat like that within 1,000 years. This phenomenon is absolutely unique.” The heat wave was analyzed to be four standard deviations above average (a 4-sigma event).
Over 55,000 deaths in Russia were blamed on the heat wave, including about 5,000-15,000 deaths from inhalation of wildfire smoke, as peat and forest fires around Moscow frequently drove air pollution levels into the brown “Hazardous” range for small particles (PM 2.5). About 2,000-2,500 drowning deaths occurred from people trying to escape the heat. A statement from the Russian Emergency Ministry said that 95% of those drowning had consumed alcohol.
Heat and drought devastated the Russian wheat crop and caused economic damages of up to $22 billion (2026 USD), prompting the government to impose export restrictions. The grain export ban, in combination with bad weather elsewhere in the globe during 2010-2011, caused a sharp spike in world food prices that helped trigger civil unrest (the “Arab Spring”) across much of northern Africa and the Middle East in 2011.
A 2012 paper, “Reconciling two approaches to attribution of the 2010 Russian heat wave,” supported the idea that the event was “mainly natural” in terms of magnitude, but that human-caused climate change had caused a threefold increase in the likelihood of the event occurring.
5. Most extreme storm of the 21st century: Hurricane Sandy of October 2012
As Hurricane Sandy headed toward landfall in New Jersey on October 29, 2012, the massive Category 1 hurricane had tropical storm-force winds that covered an area nearly one-fifth the size of the contiguous United States. The area of ocean with 12-foot seas peaked at 1.4 million square miles — nearly one-half the area of the contiguous United States, or 1% of Earth’s total ocean area. Most incredibly, 10 hours before landfall, the total energy of Sandy’s winds of tropical storm-force and higher peaked at 329 terajoules — the highest value for any Atlantic hurricane since at least 1969, and equivalent to five Hiroshima-sized atomic bombs.
At landfall, Sandy’s tropical storm-force winds spanned 943 miles of the U.S. coast. No hurricane on record has been larger. Sandy’s huge size prompted high wind warnings to be posted from Chicago to Eastern Maine, and from Michigan’s Upper Peninsula to Florida’s Lake Okeechobee — an area home to 120 million people. Sandy’s winds simultaneously caused damage to buildings on the shores of Lake Michigan at Indiana Dunes while toppling power lines in Nova Scotia, Canada — locations 1,200 miles apart.
Sandy’s storm surge caused tens of billions in damage to the Northeast and was responsible for many of the hurricane’s 159 fatalities. Had sea level held steady since 1900, rather than rising about 11 inches at New York’s Battery Park before Sandy, then the storm would not have flooded the New York City subway system as it did. Sandy’s surge was so destructive not only because of the storm’s size and strength and because of long-term sea level rise, but also because of its near-perpendicular approach to the New Jersey coast. Researchers Timothy Hall and Adam Sobel found that such a track would be expected to occur for a storm of Sandy’s strength only about once every 700 years.
Over 8.5 million customers lost power — the second-largest weather-related power outage in U.S. history, behind the 10 million that lost power during the Blizzard of 1993. Damage from Sandy is estimated at $91 billion, making it the fifth-most expensive weather-related disaster in world history, behind Hurricanes Katrina, Harvey, Ian, and Maria.
6. The most extreme weather event of the 21st century: The mid-March 2022 heat wave in East Antarctica
Even though virtually nobody was there to experience it first hand except perhaps a handful of scientists and technicians, the lonely expanse of East Antarctica was the setting for the planet’s most extreme regional weather event so far this century. This incredible warming event occurred just as the near-constant sunshine of summer – when temperatures are still frigid but far warmer than in winter – was about to switch abruptly to months of darkness.
Just days before the southern autumn equinox of March 20, 2022 – a time when temperatures have normally already plunged close to winter values – a powerful atmospheric river transported warm, moist air from the subtropics well inland across East Antarctica. As a result, temperatures soared to levels far above average over broad areas on March 18 and remained far above average for several days. Temperatures of 30-40 degrees Celsius (54-72°F) above average occurred across large areas, with a peak anomaly of 45 degrees Celsius (81°F). No other observed weather event has produced such a large departure from average over such a vast region (about 3.3 million square km). The heat wave caused widespread melting and the collapse of the Conger Ice Shelf (Fig. 5 above).
At Vostok, a Russian weather station launched in 1958, the high of -17.7 degrees Celsius (0.1°F) on March 18 smashed the record for any March by 26.8°F and came in roughly 63°F above the average daily high. The 26.8°F represents the largest margin in world history for breaking a monthly record at any site with at least 40 years of data, according to Maximiliano Herrera, an expert on international weather records. It’s also the only time Vostok has gotten above zero Fahrenheit outside of December or January, never mind mid-March. Vostok’s all-time high is -14 degrees Celsius (6.8°F).
Dishonorable mention: The 2003 European heat wave
Almost making our top-six list was the catastrophic European heat wave of July and August 2003. It set all-time national heat records in several countries, including the United Kingdom (Faversham, 38.5 degrees Celsius or 101.3°F), Germany (Roth, 41.5 degrees Celsius or 104.7°F), Switzerland (Grono, 41.5 degrees Celsius or 106.7°F), and Portugal (Amareleja, 47.3 degrees Celsius or 117.1°F).
This was the first time in more than 300 years of observations that a 100°F temperature was recorded in England, and Paris experienced an unprecedented nine consecutive days that hit at least 95°F. Many buildings lacked air conditioning, and the worst of the heat struck during the long summer holidays, which left many older adults vulnerable in scorching cities. The result was an estimated 70,000-plus “excess deaths,” a term that refers to deaths beyond what would have normally occurred at that time of year.
In the first high-profile climate attribution study ever conducted, a 2004 paper, “Human contribution to the European heatwave of 2003,” used climate modeling with and without human-added climate pollution to conclude that human influence made this heat wave about four times more likely.
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